Flashcards in Definitions Deck (39)

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31

## When are atomic propositions s and t logically equivalent?

### Atomic propositions s and t are logically equivalent if the bicondtional s t is a tautology.

32

## How does validity relate to tautology?

### argument valid IFF conditional who’s antecedent is conjunction of all premises and consequent is conclusion is tautology i.e. (P1 ^ P2 ^ …) —> C

33

## Outline the required rules of inference

### MMSS CASCA

34

## What is ex falso quodlibet and what does it show?

### Ex falso quodlibet (principle of explosion): p, -p, therefore q. It is valid!!! No rows in truth table where both premises T but C is F. This shows that as soon as there is a contradiction in your belief system, then you should believe everything.

35

## State De Morgan's laws

###
¬(p ^ q) is logically equivalent to ¬p v ¬q i.e. the negation of a conjunction is the disjunction of the negations.

¬(r v s) is logically equivalent to ¬r ^ ¬s i.e. the negation of a disjunction is the conjunction of the negations.

36

## Outline 6 steps to critically engage with an argument

###
paraphrase the argument

diagram the argument

make an ‘implicit’ critique - point out implicit propositions

make a formal critique i.e. formal fallacies

make an informal critique i.e. informal fallacies

is it sound? demonstrate that you understand what it is for each premise to be false

37

## What is the biconditional of p & q equivalent to?

### (p ^ q) v (-p ^ -q) or (p --> q) ^ (q--> p)

38

## What is a ^ -b equivalent to?

### -(a—>b)

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